In one of the methods for forming a polycrystalline silicon film, in order to form a film including an amorphous silicon film on a base, first, a silane-based gas may be supplied to a surface of a heated base (or a silicon dioxide film), and then pyrolyzed to form the amorphous silicon film on the surface of the base.
After that, a polycrystalline silicone film is formed through annealing. However, silicon migration takes place in annealing to cause agglomeration of silicon. In this process, a thickness of the surface is not uniform to increase roughness.